Host plant growth characteristics as determinants of abundance and phenology in jumping plant-lice on downy willow

1. Salix lapponum host plants at an upper altitudinal site differed significantly in size, structural density, phenology, growth performance, and spatial isolation from those growing at a lower site. 2. Plant differences were paralleled by significant differences in psyllid population density and phenology parameters, with psyllid population density, percentage of catkins occupied, and phenological development relatively lower or retarded at the upper site. Population densities at the upper site, nevertheless, remained high. 3. Plant measurements were good predictors of insect density, often explaining up to 73% of the variance in abundance among plants at a given site. 4. Sets of four plant characters identified by best subsets regression were better predictors of psyllid density and development than single factors, although differences were often not great and the combinations of characters selected by multiple regression sometimes differed from the best single predictors. 5. Best single predictors of psyllid density on catkins were measurements of plant size, particularly height, length, and basal stem diameter. Shoot density and catkin phenology were occasionally important but plant isolation and prior growth performance were less important. 6. By contrast with density, age structure of the psyllid population was predicted best from plant phenological measurements, notably catkin phenology.     

Aphid–willow interactions in a high Arctic ecosystem: responses to raised temperature and goose disturbance

Recently, there have been several studies using open top chambers (OTCs) or cloches to examine the response of Arctic plant communities to artificially elevated temperatures. Few, however, have investigated multitrophic systems, or the effects of both temperature and vertebrate grazing treatments on invertebrates. This study investigated trophic interactions between an herbivorous insect (Sitobion calvulum, Aphididae), a woody perennial host plant (Salix polaris) and a selective vertebrate grazer (barnacle geese, Branta leucopsis). In a factorial experiment, the responses of the insect and its host to elevated temperatures using open top chambers (OTCs) and to three levels of goose grazing pressure were assessed over two summer growing seasons (2004 and 2005). OTCs significantly enhanced the leaf phenology of Salix in both years and there was a significant OTC by goose presence interaction in 2004. Salix leaf number was unaffected by treatments in both years, but OTCs increased leaf size and mass in 2005. Salix reproduction and the phenology of flowers were unaffected by both treatments. Aphid densities were increased by OTCs but unaffected by goose presence in both years. While goose presence had little effect on aphid density or host plant phenology in this system, the OTC effects provide interesting insights into the possibility of phenological synchrony disruption. The advanced phenology of Salix effectively lengthens the growing season for the plant, but despite a close association with leaf maturity, the population dynamics of the aphid appeared to lack a similar phenological response, except for the increased population observed.     

The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice

There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd.     

Building supertrees: an empirical assessment using the grass family (Poaceae)

Large and comprehensive phylogenetic trees are desirable for studying macroevolutionary processes and for classification purposes. Such trees can be obtained in two different ways. Either the widest possible range of taxa can be sampled and used in a phylogenetic analysis to produce a "big tree," or preexisting topologies can be used to create a supertree. Although large multigene analyses are often favored, combinable data are not always available, and supertrees offer a suitable solution. The most commonly used method of supertree reconstruction, matrix representation with parsimony (MRP), is presented here. We used a combined data set for the Poaceae to (1) assess the differences between an approach that uses combined data and one that uses different MRP modifications based on the character partitions and (2) investigate the advantages and disadvantages of these modifications. Baum and Ragan and Purvis modifications gave similar results. Incorporating bootstrap support associated with pre-existing topologies improved Baum and Ragan modification and its similarity with a combined analysis. Finally, we used the supertree reconstruction approach on 55 published phylogenies to build one of most comprehensive phylogenetic trees published for the grass family including 403 taxa and discuss its strengths and weaknesses in relation to other published hypotheses.     

Nuclear gene trees and the phylogenetic relationships of the mangabeys (Primates: Papionini)

Phylogenetic relationships of mangabeys within the Old World monkey tribe Papionini are inferred from analyses of nuclear DNA sequences from five unlinked loci. The following conclusions are strongly supported, based on congruence among trees derived for the five separate gene regions: (1) mangabeys are polyphyletic within the Papionini; (2) Cercocebus is the sister taxon to the genus Mandrillus; and (3) Lophocebus belongs to a clade with Papio and Theropithecus, with Papio as its most likely sister taxon. Morphologically based phylogenies positing mangabey monophyly were evaluated by mapping the sequences for each locus on these trees. The data seem to fit these trees poorly in both maximum-parsimony and likelihood analyses. Incongruence among nuclear gene trees occurred in the interrelationships among Lophocebus, Papio, and Theropithecus. Several factors that may account for this incongruence are discussed, including sampling error, random lineage sorting, and introgression.      

PPCMatrix: a PowerPC dotmatrix program to compare large genomic sequences against protein sequences

Summary : An interactive dotmatrix program for the MacOS was designed that allows comparison of DNA to protein sequences using nested 3-frame translations. Availability : Shareware, available at http://copan.bioz.unibas.ch/software/ Contact : burglin@ubaclu. unibas.ch      

Thank you for not flowering: conservation genetics and gene flow analysis of native and non-native populations of Fraxinus (Oleaceae) in Ireland

The risks of gene flow between interfertile native and introduced plant populations are greatest when there is no spatial isolation of pollen clouds and phenological patterns overlap completely. Moreover, invasion probabilities are further increased if introduced populations are capable of producing seeds by selfing. Here we investigated the mating system and patterns of pollen-mediated gene flow among populations of native ash (Fraxinus excelsior) and mixed plantations of non-native ash (F. angustifolia and F. excelsior) as well as hybrid ash (F. excelsior × F. angustifolia) in Ireland. We analysed the flowering phenology of the mother trees and genotyped with six microsatellite loci in progeny arrays from 132 native and plantation trees (1493 seeds) and 444 potential parents. Paternity analyses suggested that plantation and native trees were pollinated by both native and introduced trees. No signs of significant selfing in the introduced trees were observed and no evidence of higher male reproductive success was found for introduced trees compared with native ones either. A small but significant genetic structure was found (φ_ft=0.05) and did not correspond to an isolation-by-distance pattern. However, we observed a significant temporal genetic structure related to the different phenological groups, especially with early and late flowering native trees; each phenological group was pollinated with distinctive pollen sources. Implications of these results are discussed in relation to the conservation and invasiveness of ash and the spread of resistance genes against pathogens such as the fungus Chalara fraxinea that is destroying common ash forests in Europe.